Since first coming into use in the 1970's, over the air personal paging devices have become very popular in the United States and other countries. Generally, a paging device is a small, portable, addressable, radio frequency receiving device that may be easily carried on a person, for receiving some form of message over the air anywhere within the coverage area of the transmitting apparatus for the paging system with which the device is associated. Earliest forms of pagers were addressable devices that were simply activated by a transmitted message containing address information specifically directing it to the pager. The earliest devices simply beeped or vibrated to alert the user that a message had been received, and were often referred to as "beepers" in the common vernacular. The user would normally take a predetermined action, such as calling his or her office, when the pager was activated. Early paging systems tended to cover major metropolitan areas but there was no mechanism, save acquiring multiple pagers, for making a person pagable in a number of different cities.
More recent innovations include digital and voice pagers, whereby encoded messages to call specific telephone numbers and short segments of audio are actually transmitted to the pager. Still more recently pagers for receiving, storing and displaying more lengthy alphanumeric messages have come into use.
The needs of many businesses to be able to contact individuals who travel throughout the United States has lead to the allocation of spectrum by the Federal Communications Commission to three nationwide paging systems. A nationwide paging system is one for which a subscriber may obtain a pager through which the subscriber may be contacted in any one of many metropolitan areas throughout the entire United States. One such nationwide paging system in the United States is operated by Mobile Communications Corporation of America ("Mobil Comm"), a subsidiary of the assignee of the present invention, and is known as its CityLink service.
The addressability of a pager is determined by a unique identifier or code stored within the pager that may be considered analogous to a telephone number. For historical reasons it is referred to as a "capcode" since in early paging devices, a code number was printed on a cap that fit on top of the pager. Modern paging devices used in nationwide paging systems received bilevel frequency shift keyed (FSK) encoded signals in the 930 MHz band and normally provide a single line alphanumeric display for displaying alphanumeric messages and numeric messages indicating a phone number to call. They also provide storage of multiple messages in memory for later review.
Existing paging devices used with the CityLink system, such as the apparatus currently manufactured by Motorola Corporation as its Advisor brand pager, can store both the pager specific unique capcode and an alternate capcode, also referred to as a message code, that allows the pager to decode messages with an alternate address. This is used, for example, for sending the same message to a class of recipients, such as the sales force of a corporation wherein pagers used by all sales force personnel will have the alternate capcode programmed to the same number. Additionally, such existing pagers have the ability to change the alternate capcode in response to over-the-air commands embedded in message streams generated by the paging system.
In the United States, the nationwide paging systems are of two types. In a first type of system, a message transmitted to a subscriber is distributed to all transmission facilities throughout the country and is transmitted by each facility so that if the addressed paging device is within a coverage area of one of the transmitters, the message will be delivered to the subscriber's pager. This type of system is most convenient to the user as he or she may simply turn on their paging device in any location within the coverage area of a transmitter for such a system and receive message without any further attention. However, it will be apparent from considering the architecture of such a system that the great majority of the message capacity of the system is wasted in the sense that each message is transmitted by every transmission facility in the system, but only one of them will actually deliver the message to the user's pager. Therefore, the substantial majority of the message traffic of any given transmitter will normally be occupied by messages addressed to pagers that are not within the coverage area of the transmitter. The natural result of this is that subscriptions to this first type of nationwide paging service tend to be relatively expensive.
The second of type of nationwide paging system is one for which the same paging device may be used in any coverage area within the system, but requires the user to notify the system of his or her location so that messages directed to that user will only be sent by transmission facilities in one particular area. The CityLink nationwide paging service is an example of the second type. Such a system is referred to as a segmented system in this specification. In this type of nationwide paging system each coverage area is referred to as a service area, and generally corresponds to a major metropolitan area within the United States. The entire system is composed of the collection of all coverage areas and the interconnecting links therebetween.
The user of such a system must register the presence of his or her pager in the service area in which it is located in order to received messages in that service area. Once registration is accomplished, a central message switching center receives all messages to be delivered to subscribers, maintains a record of the service area in which the subscriber last registered his or her pager. The message is then routed to transmission equipment in the appropriate service area and is ultimately transmitted by the transmission facility only within that service area.
From this, the basic trade off between the two types of nationwide paging systems will be appreciated. In a segmented paging system, the transmission facilities in all other service areas (save the one in which the user has registered) are not encumbered by sending messages to paging devices that are not within their service areas. Thus there is a very significant diminution in the amount of wasted message capacity in a segmented system. This improvement in capacity usage is obtained at the price of slight inconvenience to the subscriber, i.e., requiring the subscriber to register the presence of his or her pager is a service area as the paging device is moved out of one service area and into another. However, the great increase in utilization of capacity of the system allows the second type of service to be offered at less expensive rates than the first type nationwide paging system.
Experience with a segmented nationwide paging system has indicated that from time to time subscribers are not mindful of the requirement that they register their paging device when they enter a new service area. Registration is typically accomplished by calling a toll free (800) number, putting in a personal identification code, and letting the system know the service area in which the subscriber's paging device is now located. This information is used to update an address record indicating the current service area location for each pager in the system. When an incoming message to a particular subscriber is received at the message switching center, this information is consulted and the message is forwarded to the transmission facility at the indicated service area for transmission over the air.
When a user travels from one city to another, she will not receive her messages if she fails to register the presence of her pager in the new service area. The registration process is cost free to the user (a toll free call) and quick. It is therefore believed that failure to register upon moving to a new service area is often caused by the subscriber simply forgetting to register his or her pager. Often, beginning a day in a new city can be physically stressful if time zones have been crossed, and many times important business is the first order of the day.
Therefore, there is a need for a system that can effectively identify a subscriber to a nationwide paging service that is located in a particular service area, that has not registered in that service area, and will thus not receive messages. It is desirable for both the paging service provider as a way of increasing revenue, and for the subscriber/user so that the maximum utility from the subscription to the paging system may be obtained. It further desirable that a system for reminding the subscriber to register will generate reminders only as long as the pager is active but has not been registered in the service area so that the subscriber does not become annoyed by repeated messages requesting that the pager be registered when in fact registration has taken place.
Systems for contacting roaming cellular telephones and inquiring whether the user is interested in registering as a roamer have been previously invented by a personnel of the assignee of the present invention. However, such systems identify the roamer status of the cellular phone by information (the telephone's identification number) that is transmitted from the telephone to a cell site when the telephone autonomously registers upon entry into a new cell site. Since there is no pager to system communication for conventional paging devices, there is no similar ability to identify roaming pagers. Thus, there is no way to truly identify the presence of a roaming receive only pager in a segmented nationwide system.
It is known in the prior art to make paging devices that are specifically designed to automatically work with multiple paging systems. U.S. Pat. No. 5,196,842 to Gomez et al. describes a scanning paging device, specifically designed for use with multiple paging systems currently used in the United Kingdom. A system specific idle word is assigned to each of a plurality of separate and distinct paging systems and the idle word is transmitted at a predetermined location in a message header uniformly by multiple systems. The paging device shown in Gomez includes a table of unique idle word identifiers corresponding to the paging systems for which the user is a subscriber. So long as the unique idle word matches the stored identifier for the paging system presently in use, the pager continues to respond to messages for the identified system. When a message header is received with a unique idle word identifying another system, the Gomez device will scan its memory of authorized systems, and if a match is found, switch its configurations for the newly identified system. It also has the capability of scanning multiple frequencies used by different paging systems.
While a device such as the pager of Gomez could be used to implement an automatic switching pager for a segmented nationwide paging system, such implementation could only be made prospectively by changing the installed base of pagers from of the type currently used to the newer types such as those shown in the Gomez '842.
U.S. Pat. No. 4,644,347 to Lucas et al. shows a scanning type pager that is designed to operate on both local system frequencies and a frequency used by a non segmented nationwide system. A special code identifying that a message is transmitted on a local system is embedded in the message. When this code is detected by pager apparatus, it remains listening on the local frequency. When the special code is absent from a message format, the device assumes it has been moved to an area foreign from its home local system and automatically switches to receive messages on a non segmented nationwide system. While the device shown in Lucas '347 could also address the problem of inattention to registration in a segmented nationwide system, it, like Gomez, requires new paging devices to be used in the field.
Thus, there is a need in the art of operating a segmented nationwide paging system to provide a method of providing a reminder messages to non registered pagers that have moved into a new service area that the user should register in the new service area. This system should be usable with existing paging devices, and not generate reminders after registration is accomplished.